Field of the Invention
One disclosed aspect of the embodiments relates to a video signal processing apparatus and a video signal processing method.
Description of the Related Art
Recent digital video cameras are provided with various photographing modes for meeting users' needs. In these photographing modes, there is a mode which is characterized by, for example, photographic gamma (camera gamma). Since various gamma characteristics are provided as the photographic gamma, a gamma characteristic is selected according to the photographing mode, and gamma correction processing is performed based on the selected gamma characteristic, so that various image qualities different in gradation characteristics can be realized.
In addition, conventionally, contour correction is often performed together with the gamma characteristic. For example, in Japanese Patent Application Laid-Open No. 2008-103979, an image processing apparatus is described which performs the gamma correction on an image signal to generate a luminance signal and performs the contour correction on the gamma corrected luminance signal using a contour correction gain corresponding to a luminance amount of the image signal. Further, for example, in Japanese Patent Application Laid-Open No. 2003-230052, an electronic camera is described which determines a contour enhancement coefficient used in contour enhancement processing based on photographing information when an image is captured and performs the contour enhancement processing on the gamma corrected luminance signal using the contour enhancement coefficient.
As the gamma correction processing, processing is known which includes knee processing for compressing contrasts in middle to high luminance areas. When the gamma correction processing including the knee processing is performed, in the contour correction processing, the contour correction is strongly performed on the middle to high luminance areas in which the gradations are compressed by the knee processing. Further, the contour correction is weakly performed on low to middle luminance areas which include sufficient gradations. However, for example, when the gamma correction processing is changed from the above-described processing including the knee processing to the gamma correction processing by a different gamma characteristic due to a change of the photographing mode, the image quality may be lowered by the contour correction.